Cutout construction



Feb. 22, 1955 H. G. JEPSEN ET AL CUTOUT CONSTRUCTION Filed July 24, 1953United States Patent CUToUT CONSTRUCTION Hans G. Jepsen, Racine, Wis.,and Russell A. Wood,

Jeannette, Pa., assgnors to McGraw Electric Company, Milwaukee, Wis., acorporation of Delaware Application July 24, 1953, Serial No. 370,138.

8 Claims. (Cl. 20G-127) ThisV invention relates to cut-outconstructions.

This invention is an improvement over that disclosed in the priorpatent, No. 2,357,722 granted to Willlan'i` O. Schultz on September 5,1944, for Cut-out Construction, assigned to the same assignee, by mesneassignments, as that of the present invention.

lt is an object of the present invention to provide a cut-outconstruction which is adapted to interrupt both low amperage and highamperage faults equally well, with conventional distribution fuse links.

It is' another object of the present invention to provide a novelcartridge structure for an open-type fuse cutout, which cartridgeincludes a vent control means arranged to' provide single venting of thefuse cartridge on low current faults and double venting on faults upthrough the maximum interrupting capacity of the cutout.

It is a further object of the present invention to provide an expendablecap secured to one end of a fuse cartridge, which cap includes adiaphragm portion integral therewith operating to allow venting from`both ends of the tube at predetermined interrupting current to provide acompensating recoil action, which causes a minimum of stress on thecut-out throughout its maximum interrupting capacity rating I-t is stillanother object of the present invention to provide a fuse cut-outwherein the recoil action of the cartridge on interruption of the fuseylink is completely absorbed by the bottom hinge structure and whereinthe top contacts are not subjected to mechanical stress under faultconditions.

An embodiment of the invention is shown in the accompanying drawing, inwhich:

Fig. 1 is a side elevation of a cut-out in the form of an open type dropout fuse incorporating the essential portion of the present invention.

Fig. 2 is an enlarged fragmentary view, partly in section, showing thecontrolled venting means for operating with the fuse cartridge.

Referring to the drawings, it will be seen that the device comprises anelongated insulator 1, supported by a hanger 2 intermediate its ends,which hanger is supported by a mounting bracket 3. The mounting bracket3, as shown, is particularlyv adaptable for cross-arm mounting. Upperand lower terminal members are indicated' generallyv by the referencecharacters 4 and 5;

The upper and lower terminal members may be secured to the insulator inany suitable manner. For example, the lower terminal member S is securedby means of a strap which encircles the lower portion of the insulator'land is held clamped by means of a bolt as indicated. A cast member 7 isbolted to the clamp 6, as shown, and this member is provided with a pairof t-runnion supports in the form of hook members S, which are spacedapart and which are provided with overhanging portions 9. The castmember 7 extends downwardly and is provided with an eyelet portion 1i)to which a conductor may be tied and with a connector or clamping member11, whereby the conductor may be electrically joined and mechanicallyclamped to the terminal.

The upper terminal 4 is similarly provided with an eyelet portion and aconnector portion indicated at 12 and 1:3, respectively.

A drop-out fuse tube is provided and is indicated by the referencecharacter 14. This tube is equipped with a sleeve-like member 15 at itslower end which ts snugly over the lower end of the fuse tube. It isrigidly securedV to the lower portion of the fuse tube in any suitablePatented Feb.. 22, 1955 ice manner. For example, it may be pinned to thefuse tube, as shown in Fig. 1. A downwardly and rearwardly extending arm16 is formed integrally with the sleeve member 15Y and is provided witha keyhole-shapedrv eyelet 17, which maybe engaged by a switchstick whenlifting the fuse tube out of service after it-hasdropped to openposition, or` replacing itin the trunnion support in a well knownmanner.

A fuse link extracting lever 18 'isr p'votally mounted as indicated at19 to the arm 15 and is provided' with a thumb nut 20 screwed on athreaded pin= rigid with lever 18 to clamp a ilexiblealeader 21 of afuse link to the lever. The fuse'li'nk may be of anyy desiredconstruction and, as shown in Fig. 2, may' have a reduced' fusiblesection 22 adjacent' its upper portion and may be termi# nated in a'button head 23 at its upper end. The lever 18 is approximatelychannel-shaped at its rear portion, and is provided with a pair ofoutwardly' extending trunnions 24 which project outwardlyfrom the sidewalls of the lever 18; These trunnions areremovably received within thetrunnion supports or hooks 8. It is to be noted that the trunnions 24'can not be detached from the trunnion supports 8 until' the fuse tubehas rocked. downwardly to inoperative position. Thereafter, as stated,the fuse tube mayzbe lifted from the trunnion supports: by means of aswitch stick in the usual. manner'.

The upper terminal 4 is secured' to the upperend of the insulator 1 bymeans of a bolt, as shown, a nut being positioned in a' recess in theinsulator I and an insulating cap covering the outer end of the boltV soas to prevent birds sitting on the hanger 2 from reaching any liveportion of the upper terminal member. The specific arrangementillustrated has been fully described and claimed in U. S. Patent. No.;2,555,158, granted to W. O; Schultz for Pretensioned Spring Contact forCut'outsA on Mayl 29, 1951 and assignedto the same. assignee as is thepresent invention. T het upper terminal 4` is provided with an outwardlyextending arm 30f and a spring portion indicated generally' by thereference character The arm, or stationary portion 30 is provided with arecessed relatively narrowV neck 32 and with outwardly projectingrounded parts 33:,` A transversely extending'Y pin 34 projects: fromopposite sides.` of the stationary portion.,

The spring portion of the contact structure comprises a generallyU-shaped`r main body portion' or arms 35 whose bail part 36 ispivotallyV supported by a lipz 37' integral with the stationary member30' andslightlyy bent upwardly rearwardly of` the bail portion: toloosely and'` pivotally retain. the bail portion in place.`

The main arms 35 continue outwardly and are provided withY downwardlycurving shoulders 38 behind which the pins or projectionsl 39 of theupper terminal 4t) on the fuse tube are adapted toy normally seat. Theupper portionl of the fuse may comprise` the' sleevelike member 40,which is=` rigidly secured, as by pinning or other means to thev fusetube. Preferably a manipulating eyelet 41 is` formed integrally with theupper terminal member 40;

The downward pressure imparted by the arms* 35` of the spring portionl31. provides a yielding lockingy of the cut-out in closed position. Themain arms: 35. continue forwardly and are diverted at their ends andcurved upwardly as indicated. by the reference character 42. The spring:arm continues rearwardly by a pair of upper spring arms 43, all;portions of the springA it being understood, being integral- The springarms 43 extend rearwardly and downwardly-and: are. positioned below therounded projections 33 on the stationary portion 30;

It is to be noted particularly that these spring arms 43 bear not onlyagainst the projectionv portions. 33, but also bear against the narrownecky portion 32 ofthe stationary member 30 and thus aii'ordsy anexcellent. connection between the spring portion of. the contactindicated generally at 31 and the stationary member 30'.

It is to be noted that the pins 34 limit the downward motion of the arms35 of the springy member when the spring member is in open position.

A novel feature of the device rests in the meansv for controlling theventing of the fuse tube d'uri'ngv rupture of the fuse link, as will'hereinafter be described. This means preferably takes: the form'- of anexpendible cap which threadingly engages the outer extremity of theupwardly extending neck portion 45 formed integrally with the upperterminal 40 of the fuse tube 14. The cap 46'may be formed of anysuitable material and is screwed in place until it preferably contactsthe button head 23 of the fuse link, as shown in Fig. 2. The button headmakes contact with the conducting neck portion 45, as shown in Fig. 2.The downward pressure from the spring member 31 on the trunnion 39 istransmitted through the lever 18 to tension the fuse link towardsseparation on rupture. This tensioning will also provide excellentelectrical contact between the fuse link and the upper terminal 4. Thecap 46 is preferably of a conducting metal, which may be machined toprescribed tolerances. to provide a frangible section 47. A novel mannerof providing a frangible section is to machine the blank to provide amarginal shoulder portion 48 and a projection 49 iointly defining thefrangible section 47.

In the operation of this apparatus it will be seen that when the fuselink ruptures under overload conditions, the lever 18 will be releasedand the lower end of the fuse tube will move downwardly and outwardly,thus allowing the projections of pins 39 of the upper terminal of thefuse tube to disengage themselves from the arms 35 of the upper springcontact 31. The fuse tube will thereafter rock downwardly to inoperativeposition (not shown). Gravity assists in this action but the principaldownward force acting on the fuse tube is obtained by the heavy downwardpressure exerted by the spring contact member 31 through the arms 35,and inasmuch as the pivot 19 is located forwardly of the trunnions 24,the fuse tube will be biased toward drop-out motion.

If a light overload condition occurs, the usual expulsion action takesplace with a consequent drop-out motion of the fuse tube. The upper endof the fuse tube is completely enclosed. This allows suiiicient pressureto be built up in the tube to clear faults of the smallest magnitude.

When operations occur from a severe short-circuit, the violentexplosion, which would burst the cartridge of a cnt-out of lowerinterrupting capacity, is automatically relieved by the vent arrangementat the top of the cartridge. The frangible section 47 in the expendiblecap 46 operates to allow venting from the top as well as the bottom ofthe tube. This double venting provides compensating recoil action whichcauses a minimum of stress on the cut-out throughout its maximuminterruptina capacity rating. The position ofthe fuse link button 23 isabove the upper contact arms 43 and can be expelled unimpeded. With thetop of the cartridge as extended r by the neck portion 45. in thisposition there is nothing that would tend to detiect the gases and causeexternal ashover.

After operation, the cartridge drops out in a conventional manner toswing and hang downwardly from the trunnions 24 (not shown).

When the device is'to be refused, the lineman lifts the fuse tube fromthe lower trunnion supports by means of a switch stick engaging withinthe eyelet 17. The cap 46 is backed off the threads of the neck portion45 and may be thrown away in cases where the frangible portion 47 hasbeen ruptured because of excessive overload conditions. However, afterrupture of the fusible portion, a new fuse may be inserted in the fusetube and secured to the thumb nut 20, as shown in Fig. l. Thereafter thefuse tube is replaced in the lower tmnnion supports 8 by means of aswitch stick. The lineman then disengages the switch stick and engagesit in the eyelet 41 and rocks the fuse tube upwardly into operativeposition, as shown in Fig. l.

It will be apparent that in the case of high short circuit interruption,the lineman will have to replace the expendible cap with an entirely newcap.

Although the recessed portion of the cap may take the form of theshoulder 48, it is conceivable the cap may be grooved or otherwisemachined to rout out material from the inner surface (not shown) toprovide an annular frangible section.

The projection 49 joining the marginal shoulder portion 48 also acts toprovide a visible indicator to distinguish the expendible cap fromconventional cap members placed on ordinary cartridges provided tointerrupt relatively low current Lfaults., In` addition, the projectionhas been found to provide consistent interruption characteristicsresults on heavy overloads, which would be very unlikely if the cap hada at surface across the top.

It will be apparent that there has been provided by this invention acut-out construction which effectively utilizes an expendable andconsistently operable vent control means for the fuse cartridge, whichwill permit desired arc expulsion on low current faults and doubleventing of the tube on faults of relatively high values up through themaximum interrupting capacity of the cut-out.

We claim:

1. In a fuse construction, stationary terminals, a fuse tube having a'terminal at one end and open at the other end normally electricallyconnected to one of the stationary terminals, a fuse link having abutton head and extending through the fuse tube and electricallyconnecting the other stationary terminal and having a head engaging oneend of the fuse tube and normally in contact with the terminal of thefuse tube, and a cap normally threadingly engaging the terminal andclosing the said one end of said fuse tube, said cap having a frangibleportion integral therewith, whereby said fuse link head and a portion ofsaid cap may be blown outwardly when sutlicient pressure is developed inthe fuse tube upon rupture of the fuse link responsive to heavy overloadconditions.

2. In a fuse construction, stationary terminals, a fuse tube having aterminal at one end and open at the other end normally electricallyconnected to one of the stationary terminals, a fuse link having abutton head and extending through the fuse tube and electricallyconnecting the other stationary terminal, and a closure cap normallythreadingly engaging the terminal of said fuse tube and having amarginal recessed portion defining a frangible section integraltherewith, whereby a portion of said fuse link and at least a portion ofsaid cap may be blown outwardly when suflicient pressure is developed inthe fuse tube upon rupture of the fuse link responsive to heavy overloadconditions.

3. In a fuse construction, stationary terminals, a fuse tube having aterminal at one end and open at the other end normally electricallyconnected to one of the stationary terminals, a fuse link extendingthrough the fuse tube and electrically connecting the other stationaryterminal, and a cap normally closing the said one end of said fuse tubeand having a marginal recessed portion defining a frangible sectionintegral therewith, whereby a portion of said fuse link and at least aportion of said cap may be blown outwardly when sufficient pressure isdeveloped in the fuse tube upon rupture of the fuse link responsive toheavy overload conditions.

4. In a fuse construction, stationary terminals, a fuse tube having aterminal at one end and open at the other end normally electricallyconnected to one of the stationary terminals, a fuse link having abutton head extending through the fuse tube and electrically connectingthe other stationary terminal, and a cap normally closing the said oneend of said fuse tube and having an annular marginal recessed portiondening a frangible section integral therewith, whereby a portion of saidfuse link and at least a portion of said cap may be blown outwardly whensuiiicient pressure is developed in the fuse tube upon rupture of thefuse link responsive to heavy overload conditions.

5. In a cutout having a movable fuse tube including a terminal at oneend and open at the other end and a fuse link having a button headcontained therein, a contact assembly comprising a stationary memberprovided with a guiding head, and a spring member having U-shaped armssupported adjacent their bail portion from said stationary member andlocated on opposite sides of said guiding head and arranged to engagesaid fuse tube terminal, said spring member having rearwardly projectingarms extending from the outer ends of said U-shaped arms andpre-tensioned for movement towards each other; a cap normally closingthe said one end of said fuse tube and having a marginal recessedportion defining frangible section integral therewith, whereby a portionof said fuse link and at least a portion of said cap may be blownoutwardly when sutiicient pressure is developed in the fuse tube uponrupture of the fuse link responsive to heavy overload conditions.

6. In a cutout having a movable fuse tube including a terminal at oneend and open. at the other end and a fuse link having a button headcontained therein,

a contact assembly comprising a stationary member provided with aguiding head, and a spring member having U-shaped arms supportedadjacent their bail portion from said stationary member and located onopposite sides of said guiding head and arranged to engage said fusetube terminal, said spring member having rearwardly projecting armsextending from the outer ends of said U-shaped arms and pre-tensionedfor movement towards each other; a cap normally closing the said one endof said fuse tube and having an annular marginal recessed portiondefining frangible section integral therewith, whereby a portion of saidfuse link and at least a portion of said cap may be blown outwardly whensufficient pressure is developed in the fuse tube upon rupture of thefuse link responsive to heavy overload conditions.

7. In a drop-out fuse construction comprising an upper and lowerstationary terminal, a fuse tube having an upper terminal and being openat its lower end, a fuse link in said fuse tube having a button head andelectrically connecting the upper termina] of said fuse tube with saidlower stationary terminal, a U-shaped spring contact mounted on saidupper stationary terminal having detachably interlocking engagement withthe upper terminal of said fuse tube and biasing said tube towarddownward motion, lever mechanism pivotally supporting said fuse tubefrom said lower stationary terminal for drop-out rocking motion, saidlever mechanism controlled by said fuse link and normally holding saidfuse tube in operative position and releasing said fuse tube when saidfuse link is ruptured; a cap normally closing the upper end of said fusetube and having a marginal recessed portion defining a frangible sectionintegral therewith, whereby a portion of said fuse link and at least aportion of said cap may be blown outwardly when suicient pressure isdeveloped in the fuse tube upon rupture of the fuse link responsive toheavy overload conditions.

8. In a drop-out fuse construction comprising an upper and lowerstationary terminal, a fuse tube having an upper terminal and being openat its lower end, a fuse link in said fuse tube having a button head andelectrically connecting the upper terminal of said fuse tube with saidlower stationary terminal, a U-shaped spring contact mounted on saidupper stationary terminal having detachably interlocking engagement withthe upper terminai of said fuse tube and biasing said tube towarddownward motion, lever mechanism pivotally supporting said fuse tubefrom said lower stationary terminal for drop-out rocking motion, saidlever mechanism controlled by said fuse link and normally holding saidfuse tube in operative position and releasing said fuse tube when saidfuse link is ruptured; a cap normally closing the upper end of said fusetube and having an annular marginal recessed portion defining afrangible section integral therewith, whereby a portion of said fuselink and at least a portion of said cap may be blown outwardly whensulcient pressure is developed in the fuse tube upon rupture of the fuselink responsive to heavy overload conditions.

References Cited in the le of this patent UNITED STATES PATENTS1,853,093 Steinmayer Apr. 12, 1932 2,179,749 McCluskey et al Nov. 14,1939 2,358,684 Brown Sept. 19, 1944 2,390,670 Steinmayer Dec. 11, 1945

